Handheld audiometric device and method for hearing testing

ABSTRACT

A handheld apparatus and method for comprehensive hearing testing with pass/refer results applicable for large scale neonatal screening, adult screening, or full hearing diagnostic. The apparatus contains a signal processor, integral ear probe, and remote ear and scalp probes all packaged as a single handheld battery operated device. The apparatus preferably performs a range of tests, either independently or combined: otoacoustic measurements utilizing a novel digital signal processing method for evoked otoacoustic signal processing, auditory brain stem response test, tympanometry, and otoreflectance. Algorithms for automatic test sequence, and pass/refer indication for the tests are provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present invention is a continuation of co-pending U.S. patentapplication Ser. No. 10/019,451 filed on Dec. 27, 2001, from whichpriority is claimed, and which is herein incorporated by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

Not Applicable.

BACKGROUND OF THE INVENTION

The present invention is related generally to the field of auditorymeasurement devices and associated screening methods, and in particular,to a hand-held auditory measurement device having features beneficial toneonatal screening programs. While the invention is described withparticular emphasis to its auditory screening applications, thoseskilled in the art will recognize the wider applicability of theinventive principles disclosed hereinafter.

Universal neonatal auditory screening programs have expanded greatlybecause of improved auditory measurement capability, improvedrehabilitation strategies, increased awareness of the dramatic benefitsof early intervention for hearing impaired babies, and changes ingovernmental policies. Current neonatal auditory screening approaches,however, do not account adequately for the many different types anddegrees of auditory abnormalities that are encountered with presentscreening approaches. Because of this, individual screening tests basedon a single measurement can be influenced negatively by interactionamong various independent auditory abnormalities. Current screeningapproaches have not considered adequately the entire screening programincluding (1) physical characteristics of the measurement device i.e.,portability, physical size and ease of use, (ii) operationalcharacteristics of the device i.e., battery life, amount of recordstorage, required operating training, etc. and/or (iii) programlogistics i.e., retesting mechanisms, referral mechanisms, recordprocessing, patient tracking, report writing, and other practicalaspects. These factors can interact negatively to increase the totalcost of an auditory screening program, including the primary economiccost of screening, testing, the secondary economic cost of additionaltesting, and non-economic costs such as parental anxiety incurred whenprovided with incorrect information.

These costs, both actual and human, can be reduced by reducing the costper test, reducing the false positive rate, and resolving false positivescreening results at the bedside prior to hospital discharge. The costper screening can be reduced with a dedicated device optimized forscreening in any location and enhanced to allow effective operation byminimally trained personnel. The performance characteristic of thedevice of our invention includes reduced measurement time, the abilityto operate and configure without an external computer, the ability tointegrate and interpret all test results, the ability to store largenumber of test results, long battery life, and bi-directional wirelesstransfer of data to and from external devices.

We have found false positive results can be reduced in two ways. First,the initial screening test performance can be improved with enhancedsignal processing, more efficient test parameters, and by combiningdifferent types of tests. Second, false positive rates also can bereduced by providing a mechanism for resolving an initial screening testfailure at the bedside at the time of the initial screening. Thiscapability is provided through the availability of an automatedscreening auditory brainstem response (ABR) test capability provided bythe same device. Secondly, operational processes of a screening programcan be improved through the use of several onboard computer based expertsystems. These computer based expert systems provide improved automaticinterpretation of single test results, automatic interpretation ofmultiple test results, and improved referral processes through thematching of local referral sources with various test outcomes, such as areferral to a specific type of follow-up, whether it be a pediatrician,audiologist, otolaryngologist, or a nurse. The device disclosedhereinafter integrates in a single, hand-held device, a single stimulustransducer, a single processor and a single software application forotoacoustic emission (OAE), ABR testing, tympanometry andotoreflectance, as well as OAE simulator.

An auditory abnormality is not a single, clearly defined entity with asingle cause, a single referral source and a single interventionstrategy. The peripheral auditory system has three separate divisions,the external ear, the middle ear, and the sensorineural portionconsisting of the inner ear or cochlea, and the eight cranial nerve.Abnormalities can and do exist independently in all three divisions andthese individual abnormalities require different intervention andtreatment. Prior art physical and operational characteristics of devicesand their influences on program logistics can interact negatively toincrease the total cost of an auditory screening program. The primaryeconomic cost is the cost of each screening test though this is not theonly economic cost. A screening test failure is called a “refer” andusually is resolved with an expensive full diagnostic test scheduledseveral weeks after hospital discharge, resulting in significanteconomic cost. A substantial portion of these costs is unnecessary ifthe screening false positive rate is high. Non economic costs includeparental anxiety for false positive screening results, unfavorableprofessional perception of program effectiveness for programs with highfalse positive rates and even inappropriate professional interventionbecause of misleading screening results.

The intervention of multiple measurements into a single hand-heldinstrument allows for very important new functionality not availablewith existing neonatal auditory screening devices. This functionalityincludes (1) detection of common external and middle ear abnormalities;(2) the detection of less common sensorineural hearing loss associatedwith outer hair cell abnormalities, and (3) the detection of even lesscommon sensorineural hearing loss associated with inner hair cell orauditory nerve abnormality. Moreover, the device disclosed hereinafterhas the potential to improve the accuracy and reliability of OAEmeasurements, to allow for optimal interpretation of both the OAE andABR results, and to improve the referral process.

Attempts have been made in the past to provide the capabilities providedby the present invention. In particular, U.S. Pat. Nos. 5,601,091 ('091)and 5,916,174 ('174) disclose audio screening apparatus which purport toprovide a hand-held portable screening device. However, the screeningdevice disclosed in those patents is used in conjunction with aconventional computer, and requires a docking station for fullapplicational use. In no way does the disclosure of either patentprovide a hand-held device that can be used independently of any othercomputer. That is to say, the invention disclosed hereinafter provides adevice of significantly reduced size i.e., hand-held, which is capableof providing OAE and ABR testing, as well as tympanometryotoreflectance, and OAE simulator. It can be operated in a stand-alonemode, independently of any other computer connection, if desired. Thedevice includes a patient database, with names, and full graphic displaycapability. The device also preferably is provided with a wirelessinfrared and an RS 232 connection port to provide output directly toprinters or to a larger database where such is required.

The '174 and '091 patents also operate on a linear averaging method toremove background noise. While such method works well for its intendedpurposes, use of a linear averaging method is time consuming.Accordingly, it would be advantageous to provide a method for removingbackground noise in auditory testing which is not time consuming andwhich has improved signal reliability.

BRIEF SUMMARY OF THE INVENTION

Briefly stated, the present invention provides an effective auditoryscreening method and device are provided. The integration of an OAEscreening device and ABR screening device into a single, hand-heldinstrument enables a user to detect less common sensorineural hearingloss associated with outer hair cell abnormalities and the detection ofless common sensor hearing loss associated with inner hair cellabnormalities. In the preferred embodiment, the device includes aportable hand-held enclosure containing a digital signal processor. Theprocessor has a computer program associated with it, capable ofconducting both otoacoustic emission test procedures and auditorybrainstem response test procedures for a test subject. A display deviceis mounted to the enclosure, and displays patient information, testsetup procedure, and test results including graphing of test results.The enclosure includes a connection point for a probe, the connectionpoint being operatively connected to the signal processor. The devicealso includes an onboard power supply, making the device completely selfcontained.

A method of the present invention provides for testing OAE response in atest subject utilizing a frame overlap method of noise reduction toprovide acceptable data even in high level ambient noise conditions ofthe test subject's environment.

The foregoing features, and advantages of the invention as well aspresently preferred embodiments thereof will become more apparent fromthe reading of the following description in connection with theaccompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

In the accompanying drawings which form part of the specification:

FIG. 1 is a top plan view of one illustrative embodiment of audio screendevice of the present invention;

FIG. 2 is a view in end elevation;

FIG. 3 is a view in end elevation of the end opposite to that shown inFIG. 2;

FIG. 4 is a block diagrammatic view of the device shown in FIG. 1;

FIGS. 5 and 6 are block diagrammatic views of the algorithm employedwith the device of FIG. 1 in connection with ABR testing;

FIG. 7 is a diagrammatic view of frame sliding implemented by thealgorithm of FIG. 4; and

FIG. 8 is a block diagrammatic view of the algorithm implemented withrespect to OAE testing to improve the signal to noise ratio employedwith the device of FIG. 1.

Corresponding reference numerals indicate corresponding parts throughoutthe several figures of the drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The following detailed description illustrates the invention by way ofexample and not by way of limitation. The description enables oneskilled in the art to make and use the invention, and describes severalembodiments, adaptations, variations, alternatives, and uses of theinvention, including what is presently believed to be the best mode ofcarrying out the invention.

Referring now to FIGS. 1-3, reference numeral 100 illustrates oneembodiment of the audio screening device of the present invention. Thescreening device 100 includes an enclosure 102, which in the preferredembodiment, and for purposes of illustration and not for limitation,measures 7 1/4″ long by 3¾ wide by 1½″ deep. It is important to notethat the device 100 can be carried by the user without compromise, andtruly represents a portable hand-held device having full functionalityas described below. The device 100 includes a keyboard 5, an LCD display4, an LED pass/refer indicator 7, and an LED AC charging indicator 17.Again, by way of illustration and not by limitation, it should be notedthat the screen 4 measures, in the preferred embodiment, approximately2″ by 3 3/8″. The measurement is not necessarily important, except toshow that the LCD display is fully functional for a user, and the unitcan operate independently of any other computer system. In theembodiment illustrated, the enclosure 102 also houses an infrared port18, a compatible RS-232 port 18 a, a probe connection 90 for an earprobe 150, and an interface 103 for a plurality of electrodes 104. Theelectrodes 104 are shown attached to a conventional carrier 151.

Ear probe 150 is conventional and is not described in detail. Suitableprobes are commercially available from Etymotic Research, Part No. ER-1OC, for example. A novel feature of this invention is the provision ofan OAE simulator ear probe interface 160. The simulator function permitsa user to test the integrity of the entire OAE test system, by providingactive feedback and simulation of a test subject's ear.

Referring now to FIG. 4, a block diagram view of the device 100 is shownand described. The device 100 contains OAE, ABR and OAE simulatorcapabilities in a single, hand-held package. Preferably, the systemshown in FIG. 4 is manufactured on a single printed circuit board, withmixed signal design for both analog and digital operation. The devicepreferably is low powered, and generally operates at 3.3 volts, exceptfor the LCD 4 and some low power portions of the analog circuitryemployed with the device 100.

A digital signal processor 1 is the control for the device 100. In thepreferred embodiment illustrated, the processor 1 is a Motorola chip DSP56303. All signal processing functions described hereinafter areperformed by the processor 1, as well as the control of all input andoutput functions of the device 100. In addition, the graphic functions,user interface, patient data storage functions and other devicefunctionality are controlled by the processor 1. In conventional designlogic, the digital signal processor 1 is used for signal processing, anda separate micro controller is used for device control. We have beenable to eliminate the separate microprocessor, resulting in substantialsavings in space, cost and power consumption.

A memory subsystem 2 is operatively connected to the processor 1. Thememory subsystem 2 includes a random access memory 2 a for storingintermediate results and holding temporary variables, and a flash memory2 b for storing non-volatile, electrically programmable variables,patient data and configuration information. In the embodimentillustrated, the flash memory 2 b is substantially oversized, enable thedevice 100 to accommodate as many as 300 full patient records, as wellas multiple configurations files.

A memory mapped input/output device 3 is operatively connected to thememory subsystem 2 and to the digital signal processor 1. The memorymapped input/output 3 in turn is operatively connected to the LCDdisplay 4, the keyboard 5, the pass/referral LED indicator 7 and a realtime clock 6.

The LCD display 4 is the largest non-custom LCD available. While customLCD displays can be obtained, they add prohibitive cost to the product.The LCD display 4 provides the user with 128×256 pixels of graphics.That display is sufficient to present full waveforms of audiometrictests conducted by the device 100. The keyboard 5 preferably is amembrane switch keyboard, which incorporates only the minimum keysnecessary for operation of the device 100. All keys are programmable,except for the on/off key 105.

A real time clock 6 is operatively connected to the processor 1 throughthe memory mapped device 3. The clock 6 enables the processor 1 toprovide a time stamp for each patient and test performed, as well asproviding time signals for internal operation of the device 100.

The LED pass/refer diode 7 is used to convey test results to non-trainedusers, namely a nurse as opposed to an audiologist or otolaryngologist.Use of the LED 7 avoids confusion or misinterpretation of the LCDgraphics display 4, and allows use of the device 100 in low light areas,where the LCD display 4 may be difficult to interpret.

The plurality of analog to digital/digital to analog coder/decoders 8(codecs 8) is operatively connected to the signal processor 1. As willbe appreciated by those skilled in the art, the codecs 8 are specialintegrated circuit chips that perform analog to digital and digital toanalog conversion. The codecs 8 are operatively connected to the signalprocessor 1 along a dedicated serial link indicated by the referencenumeral 107. The codecs 8 in turn are operatively associated with aplurality of input/output devices, which provide the functionality ofthe device 100 under control of the processor 1.

An otoacoustic emission interface 9 is operatively connected to thesignal processor 1 through the associated codecs 8. The interface 9preferably is a low noise, differential analog circuit with high commonmode noise rejection.

The interface 9 is intended to drive two sound transducers inserted inthe ear canal which produce a variety of signals, from pure tones atvarious frequencies to chirps, clicks, sine waveforms etc. Theotoacoustic emission interface 9 can present tones at all standardaudiometric frequencies and sound pressure levels.

The device employed with the interface 9 includes a microphone, alsoinserted in the ear canal, which collects signals coming back from theear, and provides sufficient linear amplification to present the signalsto the codecs 8. In various embodiments of this invention, the interface9 also can be used for otoreflectance measurements for assessing somemiddle ear conditions.

The ARB interface 10 consists of a plurality of analog signal processingchips, not shown individually, which filter and amplify the signalsconnected from the scalp of a subject via electrode wires 104. In thismode of operation, the ear is presented with a repeated auditorystimulus, which causes firing of the eighth nerve, and the associatednerve pass into the brainstem. As those firings occur, electricalpotentials are generated all the way to the scalp, and there they aredetected by the electrodes 104. An additional function of the interface10 is to provide automated impedance check of the placement ofelectrodes. Once the electrodes are in place, a small current isinjected through the electrodes into the scalp of the subject, and theimpedance between electrodes is measured. Impedance can be varied byplacement of the electrodes. Once the impedance is within apredetermined range for operation, ABR signal connection can begin. Itis important to note that impedance checking can be accomplished withoutunplugging the electrodes. That is to say checking is automatic. Aslater described in greater detail, the measured ABR response is based onthe detection of a peak in the waveform in a point approximately up to15 milliseconds after a sound click, depending upon gestational age orpatient age. The actual latency of this peak is then compared to thelatency of this peak in normal hearing neonates or adults.

The otoacoustic emission simulator interface 1 I is used to check theintegrity of the OAE system. It includes a transducer or speaker and amicrophone. The microphone collects the signals presented by the OAEprobe, presents them to the codecs 8 and processor 1 for signalprocessing, and then the speaker presents the corresponding tone at thecorrect frequency and amplitude back to the original OAE probe thusproviding an active, calibrated test cavity.

The present invention optionally may include a tympanometry interface 1I a in place of the interface 11. The tympanometry interface 11 acomprises an electronic output channel to drive a miniature pump, notshown, which can produce pressure or a vacuum in the ear canal of a testsubject. A corresponding pressure sensor is used to measure thispressure, and the signal from the pressure sensor is fed into an analoginput of the codecs 8. The signal can be used as an independent feature,and the device will show full graphics output on the LCD 4 in real time.In the alternative, this test may be used in combination with the OAE orABR test to compensate for middle ear conditions.

A mode configuration system 12, a reset watchdog system 13, a crystalclock 14, a power supply 15 and a battery charger 16 all are alsopositioned within the enclosure 102 and operatively connected to theprocessor 1. While each of these blocks is required for operation of thedevice 102, they are standard in nature and are not described in detail.

The processor 1 has an input output channel 18, which are preferably aninfrared connection and an isolated RS-232 interface. The device 100 cancommunicate with any infrared compatible or RS-232 compatible personalcomputer, printer, or other digital device for data transmission. Datatransmission may include patient information, configuration data for thesignal processor 1, or software program updates.

A buzzer 19 also is provided. The buzzer 19 provides an audio feedbackto the user for keyboard actions and audio indication for errorconditions.

A serial port 20 also is operative connected to the processor 1. Theserial port 20 is utilized to provide direct programming of theprocessor 1 from a personal computer, for example, and is intended foruse only for initial software download and major software programupgrades of the processor 1.

A distortion product otoacoustic emission (DPOAE) is a tone generated bya normal ear in response to the application of two external tones. Whentwo tones, f, and f2 are applied to an ear, the normal non-linear outerhair cells generate a third tone fdp, which is called a distortionproduct. Fdp then propagates from the outer hair cells back to the earcanal where it is emitted.

The level of the DPOAE can be used as a measure of outer hair cellfunction. If the outer hair cell system is absent or otherwise notfunctioning properly, the non-linearity will be absent or reduced andthe fdp will either not be generated or generated at a lower thanexpected level.

The measured DPOAE is highly dependent upon the specific tones thatinvoke it. The frequencies of f, and f2, and their respective levels inthe ear canal, L 1 and L2 must be controlled precisely. Under knownsignal conditions, the largest distortion product is generated at a veryspecific frequency (fdp=2 f, −f2), and level Ldp. Comparison of thelevel of Ldp with known values from individuals with normal outer haircell systems forms the basis of the decision of whether the patienteither passed the screening (pass/refer LED 7) or requires a referralfor a more complete diagnostic testing.

Signals other than pure tones can be presented to the ear, which willalso evoke a response from the ear, such as clicks, chirps, etc. DPOAEis used to as an example, the other stimuli would be processed the sameway.

The processor 1 utilizes a unique method of detecting signals for theOAE test. While the method is a time domain sum and average operation,the key concept is to reuse data from adjacent frames to average withthe current frame. This method is described for the purpose of thisspecification as “sliding”. The limit to the size of the overlap is theauto correlation of original data. The method works on the assumptionthat the data within the overlap frames is different, and that the noiseis uncorrelated. It is key to keep the frame size an integer number (oneor more) of the original data cycles.

The important difference between the method of the present invention andlinear averaging is that the overlapping number M (sum operation) equals((frame number divided by (frame size minus 1)) times (frame sizedivided by (frame data cycle length plus 1))) which is larger than thereceived data frame number by a factor by which the previous frame isslid. Therefore, the expected performance of this method is better thanstandard linear averaging. In this method, the frame size divided byframe data cycle length must be an integer. The method is showndiagrammatically in FIG. 5 and FIG. 6.

The processor 1 algorithm is implemented and explained with reference toFIG. 7 and FIG. 8. As there shown, the processor 1 sends an outputthrough the digital analog converter portion of the codecs 8 through theOAE interface 9 to the ear probe utilized in conjunction with the device100. The ear probe includes a microphone which returns signals throughthe interface 9 and the codecs 8 to a new frame buffer 111 in theprocessor 1. The size of the new frame buffer 111 is calculated to be aninteger number of samples of the two primary tones at frequencies f1 andf2, and also, an integer number of samples of the otoacoustic toneproduced by the ear at fdp. This is a critical step to assure quality ofsubsequent signal processing, by avoiding windowing techniques, whichcan introduce substantial artifacts. Tables of numbers for each standardfrequency employed in the device 100 and for other frequencies in use orintended for use in the device 100 are available, and are programmedinto the algorithm once the user selects the test frequencies. Should acombination of frequencies by required for which no common integernumber can be found to fit in a practical size frame, the frame size isadjusted to fdp and the frame is windowed prior to FourierTransformation, but this method is used only in extreme cases since innormal operation, the required frequencies are available.

The data from the single frame is passed to a point Discrete FourierTransform 112 (DFT) block which calculates the signal's magnitude andphase content, but only at frequencies of interest, including fl, f2,fdp to determine a noise floor. Windowing is induced prior to DFT toreduce edge effects, although windowing induces energy at other bands.The block 112 is used only for temporary calculations, and the windoweddata is not reused again. The output of block 112 is the magnitude andphase of primary signals at f, and f2 and the noise floor figure of timeat fdp. The output of block 112 forms an input to frame rejection block113 and to an on-line calibration calculation block 114.

With the information on the magnitudes at various frequencies, a noisecalculation algorithm is employed at and around fdp to determine thenoise floor. The magnitude of the noise floor and frequency content areused against a set of predetermined conditions i.e. a comparison againstan empirically derived table contained in the processor 1, to determinethe outcome of the frame. That outcome has three distinct possibilities.First, if the noise magnitude and frame content exceed a multi-thresholdcondition at measured frequency bands, the new frame is rejected.Second, if the noise magnitudes fall between a set of reject thresholdsand a set of accept thresholds, the data in the frame is disregarded,but the noise information is kept to update the noise level average.

Third, if the noise magnitudes are below the accept thresholds, theframe is kept and passed on for further processing and the noisemagnitudes are averaged together with the noise average of the previousframe. This information is used to update thresholds, such that thesystem adapts to environmental conditions.

When the information about magnitudes of primary tones at f, and f2, andthe noise floor information at and around fdp, an online calibration ofthe level of magnitudes takes place. Several actions occur in thecalibration block 114. First, if the noise floor is large when noprimary tones are present, the frequency of the primaries is adjustedwithin predetermined limits. A new fdp is calculated, and the noisecontent of frequency bins at and around fdp is checked again. Thisprocess is repeated until a stable, low noise floor is established. Noprimary tones are played through the speaker through this process. Oncethe primaries are presented, they are stepped up to the full outputamplitude, as programmed by the user and calibrated in the ear byincreasing the output of the codecs 8. No data collection from the carhas taken place yet. At this time, if the level is not reached in a userpredetermined time, and at the rate of increase of the primaries, thetest is aborted due to lack of fit or the low quality of fit of theprobe in the ear canal. Once the proper fit is achieved, and testingbegins, data collection takes place. During the entire process of datacollection, the levels of tones at f, and f2 are checked to ensure thatthey remain within predetermined limits throughout the test. If theyexceed those limits, the output is adjusted up or down to compensateuntil a maximum compensation limit is reached, at which time, the testis aborted and the user is notified. Also, the magnitude at and aroundfdp is continuously monitored to assure low noise floor, and ifnecessary, the frequency of the primary tones are adjusted on-linewithin predetermined limits to avoid the high external noise region. Thechange in frequencies of the primaries is minimal, and within thespecified tolerances of the device 100, and have been shown not toaffect the magnitude of the tone within the ear at fdp.

The block 115 is a store/copy buffer. As a frame is collected in newframe buffer 111, a copy of it is saved for processing of the subsequentframes. The buffer 115 receives frame data from new frame buffer 111.The store and copy frame buffer 115 has a variable depth, depending thenumber of frames averaged together. Buffer 115 provides an output to ablock 116 and a block 117. The block 116 operates with the storedprevious frames, which are slid by a predetermined amount and the emptyspaces padded with zeros for subsequent processing in the averaging oldand new frame block 117.

In block 117, the frames are averaged together to reduce theuncorrelated noise present. Theoretically, the noise is reduced by afactor of one over the square root of the number of averaged frames. Theframes are averaged in a linear fashion, sample by sample and a newframe is created at the end of the averaging operation. The advantage ofthis method is that the data is essentially correlated against a slidcopy of itself, slid far enough away to avoid averaging the sameinformation content. This provides either a substantial reduction inuncorrelated noise energy for the same amount of sampling time or asubstantial reduction in sampling time to obtain the equivalent noisereduction when compared to standard linear averaging.

The minimum limit to the sliding of the data, and to the reuse of olddata frame is the autocorrelation function of the data in the frame,which can be predetermined or calculated on-line. This method isequivalent to taking much smaller frames and averaging them together.However, for the purposes of the subsequent Fourier Transformations andfiltering taking place, the frame size is required to be large (i.e.,960 samples at 48 kilohertz sampling rate), to obtain several fullcycles of each of the tones at fl, f2 and fdp. The problem with taking alarge number of very small frames is that the Fourier Transforms orother signal processing methods require several cycles of data forproper operation. The method of the present invention outperformsstandard linear averaging of large frames because of the reduction intime as well as providing proper operation of the Fourier Transforms.

The block 118 obtains the averaged data from the block 117, and collectsit in a buffer that is used for subsequent processing and signalstatistics. The output of the block 118 is digitally filtered in theblock 119. The filter 119 removes any remaining high or low frequencycomponents not required for final data presentation.

The averaged and filtered data is converted to frequency domain, in theembodiment illustrated, by using a discrete Fourier Transform in theblock 120, and the data then is ready for presentation in block 121. Aswill be appreciated by those skilled in the art, other signal processingmethods are available to convert data, and those other methods arecompatible with the device 100.

As indicated above, the device 100 enables the LCD 4 to presentinformation to a user graphically in real time on the device itself,complemented with textual and numeric information about the quality ofthe fit, amplitudes, frequency, noise floors and other relatedinformation.

Operation of the device for ABR testing is shown in FIG. 5 and FIG. 6.In ABR testing, the magnitude of the fifth peak is the one that is ofprimary interest, and the device 100 determines the magnitude of thefifth peak by counting zero crossings, after substantial filtering anddigital pre-processing. As shown in FIG. 5 and FIG. 6, the systemproceeds to count zero crossings and stores an index of an array elementupon determination of a zero crossing. If additional zero crossings arerequired, the procedure is repeated until the fifth peak is determined.Upon detection, the single waveform is isolated, and the waveform peakis correlated to find the maximum correlation sinusoid. Thereafter, thedevice 100 determines the time of occurrence of the fifth peak and thatvalue is checked against empirical data to obtain proper correlation.

Numerous variations, within the scope of the appended claims, will beapparent to those skilled in the art in light of the foregoingdescription and accompanying drawings. For example, the design of theenclosure may vary in other embodiments of the invention. Likewise, LCDdisplay 4 may be replaced with other display devices.

As indicated in the specification, we use a discrete Fourier Transformto obtain data for display. Other signal processing methods arecompatible with the broader aspects of the invention. These variationsare merely illustrative.

The present invention can be embodied in-part in the form ofcomputer-implemented processes and apparatuses for practicing thoseprocesses. The present invention can also be embodied in-part in theform of computer program code containing instructions embodied intangible media, such as floppy diskettes, CD-ROMs, hard drives, or another computer readable storage medium, wherein, when the computerprogram code is loaded into, and executed by, an electronic device suchas a computer, micro-processor or logic circuit, the device becomes anapparatus for practicing the invention.

The present invention can also be embodied in-part in the form ofcomputer program code, for example, whether stored in a storage medium,loaded into and/or executed by a computer, or transmitted over sometransmission medium, such as over electrical wiring or cabling, throughfiber optics, or via electromagnetic radiation, wherein, when thecomputer program code is loaded into and executed by a computer, thecomputer becomes an apparatus for practicing the invention. Whenimplemented in a general-purpose microprocessor, the computer programcode segments configure the microprocessor to create specific logiccircuits.

In view of the above, it will be seen that the several objects of theinvention are achieved and other advantageous results are obtained. Asvarious changes could be made in the above constructions withoutdeparting from the scope of the invention, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

1. A multi-function auditory screening device, comprising: a portable hand-held enclosure; a signal processor housed by said enclosure, said processor having a computer program operated on command by a user, said program configured to produce an auditory brainstem response test and at least at least one additional auditory test selected from a group comprising an otoacoustic auditory emission test, a tympanometry test, and an otoreflectance test for a test subject; a display device mounted to said enclosure, said display device being operatively connected to said signal processor, said display device displaying result from a selected auditory test; a probe connection point on said enclosure, said probe connection point being operatively connected to said signal processor to communicate signals associated with a selected auditory test between said signal processor and at least one auditory probe; and a power supply enclosed within sad enclosure for operating said signal processor.
 2. The screening device of claim 1 further including a plurality of electrodes for collecting data from a patient, each of said electrodes operatively connected to said signal processor to deliver signals representative of at least one test subject response to said signal processor.
 3. The device of claim 1 further including a tympanometry interface operatively connected to said signal processor, said tympanometry interface configured to measure middle ear pressure on a test subject and to adjusting minor middle ear conditions during otoacoustic auditory emission and auditory brainstem response testing.
 4. The device of claim 1 further including an otoacoustic emission interface operatively connected to said signal processor, said otoacoustic emission interface configured to acquire otoreflectance measurements of a test subject middle ear condition.
 5. The device of claim 4 further including an otoacoustic auditory emission simulator interface operatively connected to said signal processor, said otoacoustic auditory emission simulator configured for integrity testing said otoacoustic auditory emission interface.
 6. The device of claim 1 further including a memory mapped input/output device operatively connected to said memory module and to said signal processor, said display device being operatively connected to said signal processor through said memory mapped device.
 7. The device of claim 6 further including a keyboard, said keyboard being operatively connected to said signal processor through said memory mapped device.
 8. A multi-function auditory screening device comprising: a hand-held enclosure; a signal processor within said enclosure; a memory module within said enclosure operatively connected to said signal processor; a display screen mounted to said enclosure, said display screen being operatively connected to said signal processor; a computer program at least partial contained in said signal processor, said computer program being accessible by a user to operate said signal processor to perform an otoacoustic emission test and an auditory brainstem response test on a test subject.
 9. The screening device of claim 8 further including a keyboard for accessing said computer program. 